Regulation of dynamo-electric machines



Oct. 25,1927. 1,646,823

VA KARAPETOF F REGULATION OF DYNAMO ELECTRIC MACHINES Original Filed Sept. 28. 1925 Inventor: \llaciimw Karapetgffi f-lLsAttornegfi 5 effect Patented Oct. 25, 1927.

UNITED STATES; PATENT caries.

VLADIMIR: KARAPETOFF, OF ITHACA, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

REGULATION or nYNAmo-Emcrmc niAonINns.

Application flied September 28, 1925, Seria1 No. 58,978. ,Renewed August 29, 1927.

' My invention relatesto the excitation of' dynamo-electric machines and in particular to the excitation of synchronous dynamoelectric machines of .the salient-pole type 5 and has for its principal object the provision of an improved' means whereby the voltage of an alternating-current machine may be maintained substantially constant irrespective of variations in. the magnitude l0 andphase of its load current, or if desired may be made to. change under various load conditions for effecting any desired degree of compounding. A further object is the provision of an improved arrangement to substantially complete neutrahzatlon of the direct and transverse armature reaction in synchronous machines.

When a synchronous machine carries a load, either as a generator or as a motor,

the armature currents, being sources of magnetomotive forces, modify and distort the flux created by the field coils,-and thus 1nfluence the performance 'of the machine.

The traveling wave of the armature magnetomotive force may be resolved into two -waves, one whose crests coincide with the center lines of the poles, the other displaced 90 electrical degrees with respect to it. The

first component of the armature magnetomotive force produces onlya direct effect upon the field flux, that is, it either strengthens or weakens the flux without distorting it. This effect of the armature current is called the direct armature reaction. The

5second component of the armature magnetomotive force produces a transverse action, namely, it shifts the flux toward one or the dther pole tip, and may decrease the total fiux if the pole tip; become saturated.

This effect of the armature current in distorting the field flux is called the transverse armaturereaction;

These two kinds of'armature reaction may be thought of; as due to two components of the armature current, one which reaches its maximum value in time quadrature with the polar axes, namely when the corresponding group of armature conductors 1s midway between the centers of twopoles, and the to other which reaches its maximum value in time phase with the polar axes, namely a quarter of a. cycle earlier or later, that 15, when the same group of conductors is under the pole center's. Merely increasing the alternator field current in the axis of the main axis of the respective armature reactions,

varying substantially simultaneously with the variations in armature current. Compensatmg windings are placed on the field poles near the armature winding of the synchronous machine with one winding positioned to counteract the direct armature reaction and excited by a directcurrent proportlonal to that component of the armature current causing the direct reaction, and with another winding positioned to counteract the transverse armature reaction and excited by a direct current proportional to that component of the armature current causing the transverse reaction.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, to

gether with further objects and advantages I thereof, will best be understood by reference to the following description taken inconnection with the accompanying drawing in.

which Fig. 1 is a diagrammatic'representation of one embodiment of my invention as applied to a three-phase synchronous dynamo-electric machine, and Fig. 2 is an illustrative view showing a way in which the compensating windings may be arranged.

Referring to the drawing, in particular Fig. 2, 1 indicates'the stator ofa synchronous dynamo-electr'ic machine, having a re'-' volving field provided with salient poles.

The field poles 2 are provided with a main field winding 3 positioned in the usual man" ner, acompensating winding 4 arrangedcoaxially with the mam winding, and a compensating winding 5, placed in slots in the pole shoes and displaced 90 electrical degrees with respect to the windings 3 and 4. The number of turns of the windings 4 and may be arranged to provide magnetomotive forces equal and opposite to the magnetomotive forces resulting from the comvor they may bein excess, so as to compensate for the impedance dro, in the armature and, if desired, to provi e for over-compounding. The usual amortisseur winding short circuit and insert the resistance 2% in may be placed in holes 6 below the winding 5 or placed in alternate slots in the pole shoes.

In Fig. 1, an illustrative arrangement embodying my invention is shown in connection with a three-phase alternator having a stator winding 7 supplying anelectric circ uit, such as atransmission line 8. The field windings 3, 4, and 5, positioned on the rotor of the alternator in the mannerhereinbefore described, are connected to the rotor .slip

rings, 9 and 12, 10 and 12, and 1c and 11 respectively, carried on the shaft 1301: the

alternator. The-slip ringsare connectedby means of stationary'brushes 14, 15,- 16 and 17 with the exciting circuits for the field windings 3, 4, and 5. The field winding 3 is connected to a direct-current elxciter .18 through slip rings 9 and 12, and brushes 14 and 17. The exciter 18 is provided with a field winding 19 having an adjustable resistance 20 interposed in series therewith, and

an adjustable resistance 21 in series with the mains leading to the brushes 14 and 17.

A'regulator 22 of the vibratory type is provided for the exciter 18 and may consist of the usual direct-current magnet 24 connected across the exciter-mains and an alternatin current magnet 23.connected across the a lternator terminals. The vibrations of the magnets 23 and 24 may be arranged to open and close the contact 25 in av shunt circuit around the resistance 20, to alternately the eziciter field 19 in a manner well un er stood. P

. The direct current for the compensating windings 4 flnd"5 lS obtained from suitable rectifiers, for example, off-the electrondischarge type, and shown as three-phase mer cury-vapor rectifiers 26 and 33. The mercury-vapor rectifier 4 26 is provided with anodes 28, 29, and 30, a cathode 27, and a starting switch 31 and battery 32; the mercury-vapor rectifier 33 is provided with anodes 35, 36 and 37, a cathode 34, and a starting switch 38 and battery39. 'iDevices 40 and 43, referred to herein as inductance modifiers, are provided to furnish-the altcrnating-current excitation for the mercury-vapor rectifiers. The inductance modifier 40 comprises a rotor 41 of magnetic material provldedwith polar projections, but no windings, mounted on the shaft 13 of the main alternator. If the rotor is rovided with the same number of poles as t e alterwinding 42 are connected through brushes nator, it may be directly coupled to the alternator shaft, otherwise, it may be connected through gearing or rotated in such a way that electrical phase synchronism may,

ture'42' for simplicity of illustration, and

is arranged in the usual way to provide a gliding magnetomotive force. In like manner, inductance modifier 43 comprises a re tor 44 operated in synchronism with the main alternator and a stator 45 provided with-a three-phase winding 45.- The windings 42 and 45 are connected to the alter-- nator mains 8 through series transformers 53, 54, and 55. The alternating voltage obtained from the terminals 46, 47 and 48 of $5 the winding 42- is applied to the anodes 28,

29, and-"30 of the mercury-vapor rectifier 26.

The cathode 27 and the midpoint 49 of the 15 and 17, cooperating with slip rings 10 and '12, to the compensating winding '4. (In like manner, the alternating volta e obtalned from the terminals, 50, 51, an 52 of. the winding 45 is applied to the anodes 35, 36, and 37 of the mercury-vapor rectifier 33. The cathode'34 andthe midpoint 49 of the wlndlng 45-areconnected through brushes 15 and 16, cooperating with slip r ngs 10 and 11, to the compensating winding 5.

The modeof operation of the arrangement loo shown in Fig. 1 is as follows :-Assume the: alternator brought up to speed by a suit,- able prime mover (not shown) and is excited by means of the main field windin 3energ1zed by the exciter 18. Therm-load voltage may be adjusted by the adjustable resistance 21 in cooperation with theresistance .20 in the exciter field. As soon as load current is, taken from the alternator, the operation of the devices 26 and 33 will be inltlated by means of the startingswitches 31 and 38, and a direct-current voltage will be applied to thecompensating windings 4 and 5.- The stator winding. 42 of the inductance modifier 40 is excited from the alternator malns and the excitation thereof will produce a ghdmg magnetomotive force proportional to the main alternating current. The flux due to this magnetomotive force de pends upon the position of revolving polar PlOlECiLiOIlS of the rotor41. When these pro- JECtlOIlS are opposite the crest of the magnetomotive force wave, the flux is a maximum and so is the voltage at the terminals of the Winding 42. When the recesses bedesirable to adjust thechanges and reasoning applies to the device 43 and; the voltages across the terminals of the w ndings 45. Since the rotors .41 and 44 are driven from the alternator shaft and the of their respective magnetomotiveforces stators are created by the main current, the

relative position of the'gliding magneto-- 41 is so mounted that the inductance oft-he winding 42 is a maximum when the time angle equals electricaljdegrees andi the rotor 44 is set at90 electrical degrees from the rotor 41'. Thus w ith=a non-inductive current with respect to. the pole centers, the device 33 issubjected to 8, J;m l,X1 ml1In -V 0ltageand consequently the wind ng receives a large current; with a purely nductive current, thedevice 26 is sub ected ito-amaxim'um' uoltage resulting iinaazlarfge current in the winding 4; thus strengthening the compensation for the directa'rmature reaction. In a particular case it may be found displacement; angle between the rotors in ordervtoobtain some special desired excitation =for thewind -ngs 4 and 5. i

Any tendency for overcompensation-will be taken care of by the 'regulator'22,=which"- will control the excitation =in..the-field .Windings 3 in a manner well known', iand thus maintain within the values of output current "and power factor that ma actually. foccuri .ot synf chronous machines will be increas of the fact that the arrangement'herein disclosed is intrinsic and operatessubstantially in. armatur instantaneously with a change current.

j While I have shown and-described a particular embodiment ofmy inve 1. P7

lied to an alternating-current generatorit will be apparent to those-skilled mtheart that it is applicable to other synchronous dynamo-electric machines,. such, as a synchronous motor, the appended claims cover; .all- L such modifications as fall within the true spirit'and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:-

1. The combination of an alternatiii current dynamo-electric-machine provided with a main field winding and an auxiliaryfield winding, means for energizing said main field winding, means for producing an alternating voltage varying substantially as that' component of the armature current which reaches its maximum value in time quadrature with the polar axes of said main field winding, and means for rectifying said alter- 4 the voltage of the alternator at a desired value under steady load conditions in view and I,;. therefore, rain nnating voltage wherewith-the auxiliary field excitation of said alternating current machine may be varied.

2. The combination a main field winding and an auxiliary field I of an alternating-current dynamo-electric machine provided v with winding, means for energizing said main fieldwinding, means for producing an alternating' voltage varying substantially as that component of the armature current whichreaches its maximum value in time phase with the polaraxes of said main fieldwinding and means for rectifying said alter-f nating voltage wherewithrthe auxiliary: field excitation (of said valteriiating current macliineimay be varied.-

3. The como'nation ofanalternatingcurrent dynamo-electric; machine provided with. a main field winding .i-an-d auxiliary" field .1-

windings, mean for energizin said main field winding; meansforviiproducing alter-;

hating voltages one of which varies sub-- st'antially as that? component of the. armature current which reaches its maximumzin time quadrature with the polar axes of said main field winding-and another of which varies substantially as that component of the -arma-i tureacurrent which reaches its maximum in time phase with the polar axes of said-.main' field winding, and means for rectifying said.

alternating voltages wherewith" the ia uxila iary: field excitation of; saidalternati1i'g-cur-' rent machine may be varied."

4. The-combination of analternatingeuriiio rent of saidalternajting-eurreiit machine, a rotor'of magnetic material with polar-pro jections associated with said alternatingecurrent winding and arranged to be'rotated in synchronism' with said:j'alternating-current machine,-and "a rectifying device intercon' nectin'g said alternating-current winding. and

said auxiliarywfield winding for applying, thereto a: directcurrent varying in a manner to neutralize the-direct armaturereaction of said alternating-current machine.

5. "The combination of an alternating-current dynamo-electric machine provided with main field winding and an auxiliary field winding, means for energizing said main field winding, an alternating-current winding energized from said alternating-current machine for producing a gliding magnetomotive force proportional to the armature current of said alternating-current machine, a rotor of magnetic material with polar projections associated with 'said winding and arranged to be rotated in synchronism with said alternating current'maalternating-current chine, and a rectifying device interconnectin said alternating-current winding and said auxiliary field winding for applying thereto a ,direct current varying in a man nor to neutralize the transverse armature reaction of said alternating-current machine.

6. The combination of an alternating-current dynamo-electric machine provided with a main field winding and auxiliary field windings, means for energizing said main field winding, alternating-current windings energized from said alternating-current machine for producing a gliding magnetometive force proportional to the armature current of said alternating-current machine, rotors'of magnetic. material with polar'pro- 'jections associated with said alternating-current-windings and arranged to be rotated in synchronism with said alternating-current machine, and rectifying means interconnecting said alternating current windings and said auxiliary field windings for applying thereto a direct current varying in a manner to neutralize the direct and transverse armature reaction of said alternating-current ma-- chine. v u

7., The combination of an alternating-current dynamo-electric machine provided with a main field winding and auxiliary field windings, an exciter connected to said mam ,field winding, means for adjusting the excitation of said exciter in response to variations in the voltage of said alternatmg-cur-.

tralize the direct and transverse armature reaction of'said alternating-current machine.

'lhe combination of an alternating-current dynamo-electric machine provided with a main field winding, a direct-current exciter connected to said main fieid winding, an auxiliary field winding arranged coaxially with said main field winding, a poly hase winding arranged to be energized in accordance with the armature current of said eiternating-current machine, a rotor of tie material with polar projections arr: o be operated in synchronism with said a,

u l y a ternating voltage of said polyphase wind: in accordance with the variations. ti it component or the armature current nating-current machine for the a causing e rnatdirect armature reaction in s ingcurrent machine, and an charge device interconnectin' said polyphase winding and said auxiliary eld wlnding.

9. The combination of an alternating-current dynamo-electric machine provided with a main field winding, a direct-current exciter necting sai'dpolyphase winding and said auxiliary field winding.

10. The combination of an alternating-current dynamo-electric machine provided with a main field winding, a direct-current exciter connected to said main field winding, an auxiliary field winding arranged coaxially with. said main field windings, a second auxiliary field winding displaced 90 electrical degrees from the polar axis of said main field winding, two polyphase circuits arranged tobe energized in accordance with the armature current of said alternating-current machine, a rotor of magnetic material with polar projections associated with one of said. polyphase circuits and arrangedto be-operated in synchronism with said alternating-current machine for varying the alternating voltage from said polyphase circuit in accordance with the variations in that component of the armature current causing a direct armature reaction in'said alternating-current machine, an electron discharge device interconnecting said polyphase circuit and said first mentioned auxiliary field winding, a rotor of magnetic material associated with the other of said polyphasc circuits and arranged to be operated lII SyHCiHODlSHI with said alternating current machine for varying the alternatlng voltage from said polyphase circuit in accordance with the variationsin that component of the armature current causing -transverse reaction in said aiternatingcurrent machine, and an eiectron discharge device interconnecting said second mentioned pol" hase circuit and said second mentioned .1 field winding.

11. The combination of an alternatingcun ren't dynamo-electric machine provided main field winding, adirect current exciter lected to said main field winding, means for adjusting the excitation of said exciter in response to variations in the voltage of said alternating-current machine, an auxiliary' field winding arranged coaxially with ill) said main field Winding, a second, auxiliary Qfield Winding displaced 90 electricaldegrees from the polar axis of said main 'field wind ing, two polyphase circuits arranged to be 6 energized in accordance with the armature current-0f sai'd alternating-currentmachine, a rotor of magnetic material with polar pro- "polar projections displaced 90 electrical le grees Withrespect to said first rotor asmy hand sociated with the other of said polyphase circuits and arranged to be operatedin synchronism with said alternating-current machine, a. mercury-vapor rectifier interconnecting said first mentioned polyphase c1rcuit and said first mentioned auxiliary field winding, and a mercury-vapor rectifier interconnecting said second mentioned polyphase circuit and said second auxiliary field Winding,

In Witness whereof, I have hereunto set this 25th day of September, 1925.

VLADIMIR KARAPETOFF. 

